@fontSizeList: 12, 14, 16, 20, 24, 32, 42, 68, 100, 200;
.width-loop(@counter) when (@counter > 0) {
  @class: extract(@fontSizeList, @counter);
  .fs-@{class} {
    font-size: (1px * extract(@fontSizeList, @counter));
  }
  .width-loop((@counter - 1));
}

.width-loop(10);